Concentration of spodumene using flotation

ABSTRACT

A method of concentrating and recovering spodumene from an aqueous pulp or slurry by conditioning the pulp with an aliphatic primary beta-amine having from seven to 15 carbon atoms (preferably as a soluble acid salt), subjecting to flotation at a pH of about 8-10 to float off the impurities, and recovering the spodumene concentrate as residue.

United States Patent [1 1 Wyman 51 Jan. 16,1973

[54] CONCENTRATION OF SPODUMENE USING FLOTATION [75] v lnventor: Russell A. Wyman, Ottawa 8, On-

tario, Canada [73] Assignee: Canadian Patents and Development Limited, Ottawa, Ontario, Canada 22 Filed: June 29, 1970 [2]] Appl. No.: 50,936

[52] US. Cl. ..209/5, 209/39, 209/166 [51] Int. Cl ..B03b 1/04, B03d H02 [58] Field of Search ..209/166, 167, 5, 39, 40, 478

[5 6] References Cited UNITED STATES PATENTS 7/1966 Dickson ..209/166 9/1966 Maltby ..209 /2l4X 10/1968 Ray ..209/166 OTHER PUBLICATIONS Banks et 31., Min. Eng. 5(2) 181-186 (1953). Chem. Abstracts, Vol. 54, 1960, 20713b.

Primary Examiner-Frank W. Lutter Assistant Examiner-Robert Halper Attorney-Alan A. Thomson [5 7] ABSTRACT 9 Claims, No Drawings CONCENTRATION OF SPODUMENE USING FLOTATION This invention is concerned with the flotation treatment of spodumene-containing ores and minerals to separate impurities such as quartz, mica, feldspar, iron oxide and other minerals and recover a spodumene concentrate. Spodumene is basically Li,O'Al,O -4Si0 theoretically containing 8.4% Li,O but in natural deposits rarely containing above 7% H 0, and it usually occurs in association with other minerals including feldspar, mica, quartz and small amounts of iron compounds.

The use of spodumene in the glass industry (e.'g. as dense strong low expansion,thermal shock-resistant glass-ceramics) has been hindered to some extent by the presence of iron, phosphorus, and other impurities in the material. The iron impurities may occur both within the spodumene lattice and as separate iron-bearing minerals. It is possible to produce ceramic-grade spodumene of less than about 0.65% Fe,O by removal of the separate iron-bearing minerals. The best spodumene concentrate currently produced by most flotation and magnetic separations (about 0.65% Fe O is not pure enough for certain white glass-ceramics as it results in nonuniform yellow products. It would be very desirable to economically concentrate and remove iron from spodumene to a level which is well below 0.65% Fe O (preferably about 0.l% or less) and acceptable for use in white glass-ceramics. One technique has recently been described for this purpose, involving a high temperature chlorination (see The Glass Industry July 1968 p. 379-81).

It is known to separate spodumene by froth flotation using a fatty acid or its soap or a sulfonated oil as collecting agent and to recover spodumene in the flotation layer. It is also known to float the gangue away from the spodumene using certain amine salts such as tallow amine acetateand coco amine acetate (primarily C, C alpha-amine acetates).

An object of the present invention is to improve the flotation step to give a spodumene grade suitable for use in the special ceramic products mentioned above.

According to the present invention, it has now been found that an aqueous pulp of minerals including spodumene can be conditioned with an aliphatic primary beta-amine from the group having seven to fifteen carbon atoms, with the pH of the pulp being adjusted to about 8-l0 with alkali, a flotation operation carried out, and the impurities floated away leaving a high grade spodumene fraction. By this method the spodumene may be readily concentrated to about 6% U (considered to be high grade in commerce), and the iron can be reduced to less than 0.1 wt. Fe,O lf desired, a high intensity magnetic separation step can further reduce the iron to about 0.04-0.05% Fe,o,.

The primary beta-amines which may be used "have the formula where R has from five to 13 carbon atoms, and is desirably a straight chain alkyl or olefin group. Preferred beta-amines are Z-aminoheptane, 2- aminononane, 2-aminoundecane and Z-aminopentadecane (which are commercially available). These reagents are most conveniently applied as the acid salt in aqueous solution due to improved solubility.-Salts of weak acids such as acetic'are preferred, since the pH must be adjusted to the alkaline side, though the hydrochloride or other salts could be used. The amount of the amine should be sufficient to coat all of the impurity particles but an excess is uneconomical. Usually about 0.5 to 3 lb. of the amine salt per ton of ore or about 0.02 to 0.2% by wt. of solids is suitable. These amines are normally biodegradable and should not constitute a pollution problem.

It is also possible to dissolve or masterbatch the amine in a water-soluble or water-dispersible diluent such as a lower'alkanol, acetone, kerosene, mineral spirits or a'fuel oil.

The spodumene-containing material to be treated should beground to about 48 mesh Tyler Series (or 50 mesh U.S. Standard series), or preferably to 200 mesh Tyler Series 200 U.S. Standard Ser'ies). After grinding most ores of this type it is usual to deslime e.g. by adding alkali (preferably NaOH at about 1 lb. per ton) mixing, and decanting off the slimes, before the flotation. Although such slimes are usually discarded, it is a feature of the present invention that spodumene may be recovered from slimes by flotation. The solids content of the aqueous pulp should preferably be about 20 to 30 by wt. for the flotation step.

A colloidal dispersant (such as soluble starch, dextrin or known similar organic dispersant) is desirably employed to aid in dispersing and floating the impurities. The concentration of dispersant is preferably about 0.05 to 0.10 by wt. of solids. Alkali (e.g. NaOl-l) is added along with the amine salt and colloidal dispersant to give a pH of about 8-10 (preferably about 9.540), and the pulp thoroughly mixed-to condition the particles. A frothing agent such as pine oil may be added but is not essential.

The froth flotation is then carried out in the usual manner, and the impurities removed with the froth layer. The impurity fraction is usually cleaned eg by refloating 1 to 2 times to recover as much as possible of the entrained spodumene, and these cleaning fractions may be added to the spodumene concentrate.

The recovered spodumene after flotation will normally be above 6% wt. Li O, not more than about 0.1% wt. Fe o with the remainder being mainly quartz and siliceous and iron impurities. Recoveries of about 60% Li,0 are. obtained with about half of the remaining Li,0 recoverable from middlings and the remainder associated with waste. lt is desirable to process the slimes for spodumene recovery by a separate similar treatment. The ability to recover spodumene from slimes (--325 mesh material) by flotation is outstanding with these reagents. Material this fine usually fails to respond to flotation.

I EXAMPLE 1 A spodumene-containing mineral feed (2.03% Li,0, 0.14% Fe O was passed through a wet magnetic mineral separation and the nonmagnetic fraction was wet ground to substantially all minus 65 mesh, pulped with water to give a slurry of 25% wt. solids, and deslimed after addition of 0.05% wt. NaOl-l. A watersoluble starch (0.06% by wt. of solids) and 2- aminononane andcdecane (0.05% by wt. as acetate salt obtained as Armeen L-9: trademark Amour and Co.) were added together with sufficient sodium hydroxide to give a pH of 10. After agitation to condition the particles for 1-2 minutes, the pulp was subjected to froth flotation and the nonfloated solids (tails) recovered. The floated solids were cleaned by refloating twice and the fractions left behind reported as cleaner-tails. The results were as follows:

TABLE 1 Li,0 Wt.% Fe,0 Li,0 recovery of feed wt. wt. wt. Tails (spodumene fraction) 15.6 0.05 6.28 52.5 Cleaner-Tails 2.1 0.26 5.49 6.2 Combined 17.7 0.075 6.19 58.7

The floated impurities were mainly mica, quartz, feldspar and iron oxide.

EXAMPLE 2 Another feed sample (2.03% U 0, 0.14% Fe o was processed as in Example 1 using 0.08% by wt. 2- aminononane and-decane acetate but after flotation the tails (spodumene fraction) were screened on 200 mesh and each fraction passed through a high intensity wet magnetic separator. The results were as follows:

TABLE 2 Fe O Li,0 Tails Fraction Wt.% Wt. Wt.% Wt.% Fe,0 Li,0 magnetic 0.6 200 mesh 93 non-magnetic 99.4 0.04 6.11

magnetic 4.4 200 mesh 7 non-magnetic 95.6 0.06 7.30

EXAMPLE 3 A spodumene-containing mineral feed (2.23% Li O, 0.10% Fe O was dry-ground to substantially all 48 mesh (Tyler). One half, A, was then wet ground to approximately minus 65 mesh,deslimed after adding 0.05% by wt. NaOH and the deslimed part conditioned with 0.05 wt. NaOH, soluble starch (0.06 wt. and tallow amine acetate (0.08 wt. as Armac T-trademark Armour and Co.). The second half, B, was treated the same way except that 0.06 wt. of 2- aminononane and-decane acetatewas substituted for the Armac T. Both parts were then subject to froth flotation and the floated (concentrate) and non-floated (tails) materials recovered. The floated impurities were given two cleaning treatments as in Example 1, and the non-floating material combined as "cleaner-tails". The spodumene-rich tails were passed through a high intensity wet magnetic separator. The results were as follows:

Tails (spod.). 21.1 0.23 5.91. 21.0 0.12 6.20

(57.7 (59.6) Combined 100.0 0.14 2.16 100.0 0.11 2.18 Non-Mags 20.6 0.09 6.15 20.6 0.05 6.12

" wt. recovery of L- It is evident from these examples that the use of the beta-amines according to the present invention (com- EXAMPLE NO. 4 (Tests, C, D and E) A spodumene-containing mineral feed (2.23% Li O, 0.10% Fe,03) was dry-ground to 48 mesh (Tyler). It was then wet-ground to approximately 65 mesh as was done in Example 3. Separate portions were deslimed for each of the tests comprising the example after adding 0.05% by wt. NaOH. The deslimed portions were conditioned after adding 0.05% by wt NaOH and 0.06% by wt soluble starch. For Test D, 0.12% of 2-aminoheptane acetate (obtained as Armeen L-7; trademark Armour and Co.) was added as collector. For Test E, 0.07% wt of Z-aminononane and-decane acetate, and for Test C, O. 12% wt of 2-aminoundecane acetate (obtained as Armeen L-l 1: trademark Armour and Co.) were added as collectors. The pulp was subjected to froth flotation in each test and the floated (concentrate) and non-floated (tails) recovered. The floated impurities were given two cleaning flotation treatments with the non-floated comprising cleanertails. The slimes portions in each test were conditioned with 0.01% wt NaOl-l, 0.04% wt soluble starch, and 0.01% wt of the specified collector. They were then subjected to froth flotation and the concentrate and tails recovered. The results were as shown in Table TABLE 4 Test D (C,, 0.12% wt.) Test E (C,, 0.07% W1.) Product wt Fe,O= Li,0% wt Fe,0, Li,0

v Slime Conc 20.4 0.10 1.51 24.6 0.10 0.95 Coarse Conc 7.4 1.20 0.66 48.0 0.10 0.35

Cleaner Tails 24.1 0.08 0.58 5.7 0.13 3.76 Tails 38.5 0.08 2.48 17.5 0.09 5.80 (63.3) (56.9) Slimes Tails 9.6 0.09 1.70 4.2 0.09 3.77 (8.9) TestC(C,,,0.12%Wt.) Product wt Fe,0, Li,0

Slime Conc 22.2 0.14 1.18 Coarse Conc 52.0 0.21 0.50

Cleaner- Tails 3.7 0.18 2.90 Tails I 18.1 0.14 6.06 (56.8) Slimes Tails 4.0 0.14 5.22

' Bracketed figures are Wt. recovery of L110.

11: 0, in -coarse concentrate and low Li,O in tails. It

was noted also that alkali content of the spodumene (tails).decreased with increasing length of carbon chain in collector. The possibility of balancing these factors by employing mixtures of the beta-amines (synergistic effect) as collectors is indicated, although the C9 com: pound largely provides a desirable balance and also is effective at much lower concentration than the C7 and C11 compounds.

The tests further demonstrate the ability of betaamines to effect selective flotation in the slime portion with very little additional collector. This is a very important attribute because slimes are normally discarded as untreatable, or because they can only be floated with large amounts of collector.

I claim:

1. A method of recovering spodumene from an aqueous pulp by flotation of impurities including siliceous and iron minerals, the flotation consisting essentially of a. conditioning the pulp with an aliphatic primary beta-amine having from nine to ll carbon atoms, in the presence of sufficient alkali to give a pH of about 8l0,

b. subjecting the conditioned pulp to the flotation operation whereby the siliceous and iron mineral impurities are concurrently floated away from the spodumene, and

c. recovering the spodumene fraction.

2. The method of claim 1 wherein a dispersant selected from starch and dextrin is present during conditioning.

3. The method of claim 1 wherein the beta-amine is added in the form of a water-soluble acid salt.

4. The method of claim 3 wherein the acetate salt of 2-aminononane or Z-aminodecane is used.

5. The method of claim 3 wherein the salt is added in amounts from about 0.02 to 0.2% by wt. of the solids.

6. The method of claim 1 wherein the pH of the conditioned pulp is about -10.

7. The method of claim 1 wherein the recovered spodumene fraction is subjected to a high intensity wet magnetic separation step.

8. The method of claim 1 wherein the amine is 2- aminononane or Q-aminodecane.

9. The method of claim 1 wherein the amine is a mixture of 2-aminodelane and Z-aminononane. 

2. The method of claim 1 wherein a dispersant selected from starch and dextrin is present during conditioning.
 3. The method of claim 1 wherein the beta-amine is added in the form of a water-soluble acid salt.
 4. The method of claim 3 wherein the acetate salt of 2-aminononane or 2-aminodecane is used.
 5. The method of claim 3 wherein the salt is added in amounts from about 0.02 to 0.2% by wt. of the solids.
 6. The method of claim 1 wherein the pH of the conditioned pulp is about 9.5-10.
 7. The method of claim 1 wherein the recovered spodumene fraction is subjected to a high intensity wet magnetic separation step.
 8. The method of claim 1 wherein the amine is 2-aminononane or 2-aminodecane.
 9. The method of claim 1 wherein the amine is a mixture of 2-aminodelane and 2-aminononane. 